Individual eccentric control for mill screwdown

ABSTRACT

In a beam-backed rolling mill wherein the working rolls are backed by casters mounted on eccentric shafts for screwdown purposes, there is disclosed an arrangement wherein a plurality of eccentrics are mounted at spaced intervals on a shaft, each of said eccentrics being individually operable by outside means, whereby the eccentrics may be made large enough so as not to be self-locking, and whereby the pressure exerted by each eccentric, through the adjacent caster, upon the work roll, may be controlled and the roll profile adjusted to a desired configuration.

United States Patent Tadeusz 51 Sept. 19, 1972 [54] INDIVIDUAL ECCENTRICCONTROL FOR MILL SCREWDOWN Inventor: Tadeusz Sendzimir, 0/0 T. SendzimirInc. PO. Box 1350, Waterbury, Conn. 06720 Filed: May 25, 1971 Appl. No.:146,661

US. Cl. ..72/242, 72/243, 72/244 Int. Cl ..B21b 29/00, B2lb 31/26 Fieldof Search ..72/243, 240, 244, 245, 242

References Cited UNITED STATES PATENTS 8/1939 Sendzimir ..72/242 X8/1949 Sendzimir et al. ..72/243 X 3,147,648 9/1964 Sendzimir ..72/243 XPrimary Examiner-Milton S. Mehr Attorney-Melville, Strasser, Foster 8:.Hoffman [57] ABSTRACT In a beam-backed rolling mill wherein the workingrolls are backed by casters mounted on eccentric shafts for screwdownpurposes, there is disclosed an arrangement wherein a plurality ofeccentrics are mounted at spaced intervals on a shaft, each of saideccentrics being individually operable by outside means, whereby theeccentrics may be made large enough so as not to be self-locking, andwhereby the pressure exerted by each eccentric, through the adjacentcaster, upon the work roll, may be controlled and the roll profileadjusted to a desired configuration.

15 Claims, 6 Drawing Figures PATENTEDsw 19 m2 SNEET 2 0F 2 INVENTOR jTADEUSZ SENDZIMIR ELVXLLE STRASSER, FOST ER and HOFFMAN INDIVIDUALECCENTRIC CGNI'ROL FOR MILL SCREWDOWN BRIEF SUMMARY OF THE INVENTION Inbeam-backed mills such as are disclosed in Sendzimir U.S. Pats. Nos.2,479,974 and 3,l47,648, screwdown is accomplished by changing theangular position of eccentric shafts which carry backing casters betweenspaced eccentrics. A change in the angular position of the eccentricshafts produces a parallel displacement of the work roll in a directionnormal to its axis. To obtain deviations from parallelism, i.e. tochange the roll profile, each of the eccentrics is provided with aneccentric bushing, and the angular position of each of the bushings iscontrolled individually. Necessarily these spaced eccentrics are verysmalljust enough to cover the screwdown range, and therefore screwdownactuating means must be provided at each end of the eccentric shafts tominimize torsional deflection. Since, however, small eccentrics areessentially self-locking, they cannot be used to control the rollpressure exerted on each eccentric, even through they control preciselythe position of the roll.

The present invention provides means for precisely controlling thepressure exerted by each eccentric (through the adjacent casters) uponthe roll; and these means control the roll pressure at spaced intervalsacross the entire width of the work piece.

These is provided a shaft carrying the eccentrics, and each eccentric isconnected to outside means for exerting torque upon it and/or forrotating it. In this way torsional deflection of the shaft is avoidedand therefore the eccentrics may have much greater eccentricity. Whenthis factor is combined with the use of suitable anti-friction bearings,the eccentrics are far removed from the self-locking range. Furthermore,angular adjustment of these eccentrics results in a roll displacement(screwdown range) which is many times larger than is obtainable in millsheretofore known, so that the mill of the present invention is useful incertain fields which are out of reach of the small eccentric mills, aswill be discussed in more detail hereinafter.

DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS FIG. 1 is a fragmentarytop plan view with parts in cross sections of one embodiment of theinvention.

FIG. 2 is a vertical cross sectional view taken on the line 2-2 of FIG.1.

FIG. 3 is a composite view similar to FIG. 1 showing a second embodimentin the left half and a third embodiment in the right half.

FIG. 4 is a vertical cross sectional view of FIG. 3 also showing thesecond and third embodiment.

FIG. 5 is a schematic elevational view of an application of theinvention; and

FIG. 6 is an enlargement of a central portion of FIG. 5 showing amodification.

DETAILED DESCRIPTION As shown in FIGS. I and 2, the mill is providedwith saddles I supported by the rigid beam 2 of the mill housing andspaced evenly across the width of the work piece. Each saddle 1 has twoopenings to accommodate the eccentrics 3, 3' with their bearings such asthe needie bearings 4, 4'. The eccentrics 3, 3' in turn carry shafts 5,5' which support casters 6, 6' which are mounted upon the shafts in thespaces between adjacent eccentrics 3, 3'. The casters 6, 6' jointlysupport one component of roll pressure exerted by the working roll 7along their common generant.

Further description of the invention of FIGS. 1 and 2 will be withrespect to the elements 3', 4', 5 and 6', and it will be understood thatthe parts to be described hereinafter will be duplicated for theelements 3, 4, 5, and 6.

It will be observed in FIG. 2 that portions of the eccentrics 3'protrude beyond the diameter of the casters 6'. To those protrudingportions there are attached the gear segments 8'. These may be attachedby screws, bolts, or similar means, and they engage arcuate keyways 9'provided in the protruding portions of the eccentrics 3. A shaft 11'carries pinions l0 keyed thereon and the pinions 10' are in mesh withthe respective gear segments 8'. The shaft 11' is located in a saddle oran extension 1" thereof by bearings 12' and the shaft 11' is coupled toactuating means such as the hydraulic actuator 13'.

It will now be clear that a change in the angular position of the shaft11 produced by operation of the actuator 13' causes a change in the rollgap (screwdown) which will be parallel across the width of the workpiece since all the eccentrics 3 are identical.

During rolling, the roll pressure (roll separating force) must becounterbalanced by the torque of the actuator 13', acting through thepinions I0, segments 8', eccentrics 3', casters 6 and shafts 5'. Asindicated above, corresponding parts operate through the me mbers 3, 4,5, and 6. In order to control the distribution of this torque among theseveral eccentrics 3' and thus to control the distribution of rollpressure across the width of the strip, the axial position of eachpinion 10' is adjustable. This may be accomplished by means of nuts 14'engaging threaded hubs of the pinions 10'. The outer peripheries of thenuts 14 are provided with worm gear teeth which engage worms 15' whichcan be rotated by means of gear motors I6 and the like. Since the teethon the segments 8' and the pinions 10' are helical, an axialdisplacement of a pinion 10' will alTect the share of the load it takeswith respect to the total torque exerted by the actuator 13'. The gearmotors 16' may be controlled by signals from strip flatness verifyinginstruments of the automatically produced flat sheets, as will bedescribed hereinafter. A suitable relief valve (not shown) is preferablyprovided in the hydraulic system of the actuator so that in cast of asurge of roll pressure, as for example during a cobble, the actuatorsmay actually turn in reverse, thereby preventing damage to millcomponents.

Further advantages of prior art arrangements, as exemplified by US. Pat.Nos. 2,479,974 and 3,147,648, lie in the increased rigidity andsturdiness of the screwdown elements. The eccentric screwdown shaftsshown in said patents are limited in diameter by the inside diameter ofthe casters; and it is therefore necessary to apply torque means to bothends of the eccentric shafts in order to avoid an eccentricallytorsional deflection.

On the contrary, while the actuator shaft ll of the present inventionfulfills the same role, it is not subject to any limitation as to itsdiameter. it can be made so heavy, that even though the torque means(hydraulic actuator) is applied to one end only, the torsionaldeflection will be negligible.

The space limitation of the prior art is still more acute when appliedto crown control elements, which are slender eccentric rings surroundingthe screwdown eccentrics and having needle bearings inside and out toreduce friction. These elements are moreover subjected to the same rollpressure as the screwdown eccentrics and must, therefore, be made ofheat-treated and ground alloy steel. This, of course, increases theircost.

As distinguished from this, crown control according to the presentinvention does not require separate elements since the screwdownelements serve both purposes. These parts are sturdy and can be made ofordinary machine steel and they are not subjected to roll pressure.

Turning now to FIGS. 3 and 4, the left and right-hand portions of theseFigures differ from each other only in the mode of attachment ofactuating means to the eccentrics 3 and 3'. In the case of mills wherethe utmost capacity of the casters 6 is not required so that a greaterspace between them is permissible the saddle 1 and eccentric 3 may bebroadened and the segment 8 may be affixed to the eccentric 3 in ashallow slot 17 therein and the parts may be connected by dowels,screws, or the like as at 18. The tooth segment 8 protrudes from thesaddle 1 through a slot 20 provided therein and it protrudes to aposition in which it meshes with a pinion as described above. Thisconstruction makes it possible to apply the tooth pressure in the planeof symmetry of the eccentric 3.

The structure shown on the right-hand side of FIGS. 3 and 4 difl'eres inthat the saddle l' is open. That is to say, there is no continuousbearing around the eccentric 3'. Thus, the free part of the eccentric 3'is accessible and an arm 21 may be attached to it by screws 22 and thearm 21 may be pivotally connected to the piston rod 24 of an oscillatingfluid cylinder 23. it will, of course, be understood that each of theeccentrics 3' is provided with the actuating mechanism just described.With the type of saddle shown in the right hand half of FIGS. 3 and 4,with the saddle being open, the saddle is subject to bending moment bythe horizontal component of the roll pressure. To counteract this, thebase of the saddle where it contacts the beam 2 of the housing isextended to a point a farther away from the eccentric.

To open or close the roll gap, fluid may be admitted to or let out fromall the cylinders 23 connected to the eccentrics 3' of a shaft 5simultaneously. It will be observed that a three-way valve 25 isprovided for each cylinder 23 and this valve has connections to a pumpor supply of fluid under pressure S to a sump W and to an individualpressure control device, such as the small accumulator 26 which isconnected by a suitable valve 25' to both the supply S and the sump W.The several valves 25 for the several cylinders 23 may be arranged in asingle line and connected by a shaft 35 so that they may all be operatedconcurrently. In the third position mentioned above, pressure from eachcylinder is controlled individually and independently of the othercylinders.

In the first position of the valve, causing the rolls to close, the roll7 abuts against its cooperating roll through the work piece which isbetween the work rolls. The opposite roll does not require positioningso that all the eccentrics can be omitted from its shaft 5. For openingthe rolls in the second position of the valve 25, stroke limiters can beprovided in the cylinders 23.

It will be clear from the foregoing description that a great advantageis provided by the mechanism just described, in that it permits the useof large eccentricities so that when the eccentrics are mounted inantifriction bearings, they operate far from the self-locking range.When torque is applied to an eccentric, a certain force is exerted bythe adjacent casters upon the work roll 7. This force is a function ofthe magnitude of the torque and of the angular position of theeccentric. Assuming that this force is of a magnitude capable ofproducing the desired reduction in the thickness of the work piece, theabove described feature means that if the entering work piece ischanging the thickness, for example becoming thicker, then the eccentricwill permit the roll gap to increase while the roll pressure will staysubstantially the same. This feature is of fundamental importance inmills for skin-passing" where a predetermined, usually light, percentualelongation must be accurately maintained to produce a work piece (steelstrip) having the required physical properties. If the roll gap did notchange under the circumstances 30 just outlined, the percentualelongation would have increased with the result that the steel stripwould have become harder and less ductile.

A typical application of such a skin-pass mill is in strip processing,for example in a continuous bright-annealing line. A schematic view ofsuch a mill is shown in FIG. 5 and it will be observed that the annealedand cooled strip 27 is passed in succession by two tensioning deviceswith the skin-pass, mill therebetween. While the strip 27 is passedthrough the line at a certain tension, the tension is considerablyaugmented for skinpassing and usually amounts to one-third of theelastic limit of the strip.

As shown, each tensioning device consists of a pulley 28, 28' aroundwhich the strip passes and two deflecting pulleys 29, 29', and in somecases pressure roll chains 30, 30 around each tension pulley, so thatwith high enough initial tension, the wrapping angle around the tensionpulley and its coefficient of friction, a nonslip contact is assured.The tension pulleys 28, 28' are preferably geared together and operatedfrom a common drive, so that with the strip moving from left to right,the pull y 28 is driving and the pulley 28 is driven, while thedifference in surface velocities of the two pulleys must be equal to therequired percentual elongation of the strip 27. Known compensationdrives such as described in US. Pat. No. 2,l94,2 l 2 are usually usedfor adjustment of the percentage of elongation without jeopardizing theaccuracy thereof.

It will be clear that correct roll pressure is a pressure where thetension of the strip 27 is of the desired magnitude (one-third of theelastic limit preferably). If the tension falls, this can be correctedby lowering roll pressure. If not corrected, it is difficult to producea flat strip. Similarly, if the tension is too high, the strip 27 maystretch irregularly at places outside of the roll bite, producingso-called stretcher-strains" and making the strip unsuitable for manypurposes.

in the mill disclosed in FIG. 5, it is easy to fulfill these conditionsat all points across the width of the strip and to do thisautomatically, thus producing a strip that is notonly correctlytemper-rolled (skin-passed) but is also perfectly flat. For thispurpose, tension indicating meters are provided at points across thestrip corresponding to the positions of the eccentrics 3. These metersmay be proximity gauges 31 mounted on a rigid beam 32 parallel with thewidth of the strip. The strip is then subjected to a light but uniformpressure, such as static air pressure. This pressure may be produced ina trough 33 extending all the way across the strip and closely spaced tothe strip to restrict escape of air and air under pressure is suppliedthrough the line 34 from a blower or the like. it will be clear that thehigher the tension in a particular portion of the strip, the less itwill deflect toward the proximity gauge 31. The indications of thegauges 31 may be transmitted in the form of suitable signals to thepressure control device of each cylinder 23 to restore uniform tensionacross the strip 27. This insures that the flatness is correct and atthe same time controls the total pressure to assure correct rollingconditions, including correct tension.

Another quite different benefit of the present invention, when appliedto skin-passing and processing lines, is the possibility of providingtwo pairs of work rolls rather than one. Only one of the pairs is inworking contact with the strip, while the other is retracted and keptfar enough from the strip to prevent contact, even on wavy spots in thestrip.

These skin-passing lines are operated without interruption for weeks ata time and any stoppage for roll changing is intolerable, since thethermal balance of the heat treating part of the line must not be upset.Such an upset produces costly scrap losses. According to the presentinvention, the operation of withdrawing one and engaging the other pairof work rolls involves only the turn of the eccentrics and takes only afraction of a second. P10. 5 shows the left-hand pair of rolls 7 inworking contact and the right-hand pair 7' out of contact with thestrip. Therefore, the left-hand eccentric shafts 5 have their eccentrics3 turned toward their respective rolls 7, while the right-hand eccentricshafts 5' have their eccentrics 3' turned away from their rolls 7'. Themiddle shaft 5" has no eccentrics and its casters 6 rotate around fixedcenters.

in cases where it is desired to increase still further displacement ofthe roll, the middle shaft 5" may also be actuated for the purpose. Asshown in FIG. 6, the middle shaft 5" may have its eccentrics keyed ontoit and a rotary actuator is coupled onto one of its ends to rotate it toone of two positions: to the left as shown in FIG. 6 to engage the roll7 while disengaging the roll 7'; or to the right to disengage the roll 7and engage the roll 7'. it will be noted that in the configuration ofFIG. 6, the axis of the work roll 7, the casters and eccentrics, all liein the same plane. These keyed eccentrics may be relatively large toobtain a large displacement of the rolls since in either of the twooperating positions the roll pressure passes directly through the centerof the eccentrics, so that the eccentrics and the shaft 5 are notsubjected to any torque.

It will be clear that numerous modifications may be made withoutdeparting from the spirit of the invention and no limitations notspecifically set forth in the claims is intended or should be implied.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. in a beam-backed mill for rolling flat articles, said mill havingwork rolls backed by casters mounted on eccentrics, which are in turnmounted on caster shafts, said caster shafis being disposed in saddlesprovided between adjacent casters, said eccentrics providing for controlof the roll gap; lever means attached to each eccentric and extendingbeyond the periphery of said casters, screwdown actuating devices, andmeans individually connecting said lever means and said actuatingdevices.

2. The structure of claim 1, wherein said eccentrics extend beyond theperiphery of said casters so as to expose an arcuate segment thereof forattachment of said lever means.

3. The structure of claim 1, wherein slots are provided in saideccentrics in which said lever means are secured, and slots are providedin said saddles, through which said lever means protrude and oscillatethrough their screwdown range.

4. The structure of claim 1, wherein said saddles are open so as toexpose portions of said eccentrics for attachment thereto of said levermeans.

5. The structure of claim 4, wherein the bases of said open saddles areextended beyond said eccentrics to increase the resistance of saidsaddles to bending.

6. The structure of claim 1, wherein said lever means are provided withgear teeth, and said screwdown actuating means incorporate gear teethmeshing with the teeth on said lever means.

7. The structure of claim 6, wherein an actuator shaft is mountedparallel to said caster shaft beyond the periphery of said casters, andcarries a plurality of pinions keyed thereon, said pinions being inmesh, respectively, with the teeth on said levers, whereby a change inthe angular position of said actuator shaft results in simultaneousactuation of all the eccentrics to produce parallel movement of saidcasters.

8. The structure of claim 6, wherein the teeth on said levers andpinions are helical, and means are provided to adjust the axial positionof said pinions on said actuator shaft, so as to control thedistribution of tooth pressure among the several lever means of saidcasters.

9. The structure of claim 1, wherein said screwdown actuating means arelinear actuators.

10. The structure of claim 9, wherein said linear actuators are fluidcylinders with actuating pistons.

l l. The structure of claim 10, wherein a fluid circuit is provided forall said cylinders, said circuit including a source of fluid pressure, asump and an individual pressure control for each cylinder, and a valveis provided for each cylinder, all said valves being connected togetherfor simultaneous operation to (a) admit fluid from said source, (b)discharge fluid to sump, or (c) to close both said connections and opena connection to said individual pressure controls.

12. The structure of claim 1, wherein two pairs of work rolls and threepairs of casters are provided, the central pairs of casters having noeccentrics, and only the two pairs of outer casters are connected tosaid screwdown control means.

13. The structure of claim 12, wherein at least one of the pair ofcentral casters carries eccentrics, said eccentrics being connected toan actuator arranged to shift said casters from one position in whichthe axes of the casters, caster shafts, and eccentrics, and one of thework rolls lie in the same plane, to a symmetrical position with respectto the other work roll, whereby to engage one pair of work rolls whiledisengaging the other. 14. The structure of claim 1, in combination withmeans to deflect a tenioned exiting strip in a direction normal to itsplane, and proximity measuring gauges disposed opposite each of saideccentrics to measure the deflection of the strip at that point, thesignals from eccentric control means to said proximity gauges serving toactuate the individual IINITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 3, 91,810 Dated September 19, 1972 Inventor)Tadeusz Sendzimir It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Claim 1, column 6, lines 6 and 7, the phrase "eccentric,

which are in turn mounted on caster shafts, said caster shafts" shouldread caster shafts carrying eccentrics, said eccentrics Signed andsealed this 19th day of March 19%..

(SEAL) Attest:

EDWARD M.FLETCHER,JR. C. MARSHALL DANN Attesting Officer Commissioner ofPatents USCOMM-DC 60375-P69 FORM PO-1050 [10-69) w u.s. GOVERNMENTrnnmua omcz: mu o-au-au

1. In a beam-backed mill for rolling flat articles, said mill havingwork rolls backed by casters mounted on eccentrics, which are in turnmounted on caster shafts, said caster shafts being disposed in saddlesprovided between adjacent casters, said eccentrics providing for controlof the roll gap; lever means attached to each eccentric and extendingbeyond the periphery of said casters, screwdown actuating devices, andmeans individually connecting said lever means and said actuatingdevices.
 2. The structure of claim 1, wherein said eccentrics extendbeyond the periphery of said casters so as to expose an arcuate segmentthereof for attachment of said lever means.
 3. The structure of claim 1,wherein slots are provided in said eccentrics in which said lever meansare secured, and slots are provided in said saddles, through which saidlever means protrude and oscillate through their screwdown range.
 4. Thestructure of claim 1, wherein said saddles are open so as to exposeportions of said eccentrics for attachment thereto of said lever means.5. The structure of claim 4, wherein the bases of said open saddles areextended beyond said eccentrics to increase the resistance of saidsaddles to bending.
 6. The structure of claim 1, wherein said levermeans are provided with gear teeth, and said screwdown actuating meansincorporate gear teeth meshing with the teeth on said lever means. 7.The structure of claim 6, wherein an actuator shaft is mounted parallelto said caster shaft beyond the periphery of said casterS, and carries aplurality of pinions keyed thereon, said pinions being in mesh,respectively, with the teeth on said levers, whereby a change in theangular position of said actuator shaft results in simultaneousactuation of all the eccentrics to produce parallel movement of saidcasters.
 8. The structure of claim 6, wherein the teeth on said leversand pinions are helical, and means are provided to adjust the axialposition of said pinions on said actuator shaft, so as to control thedistribution of tooth pressure among the several lever means of saidcasters.
 9. The structure of claim 1, wherein said screwdown actuatingmeans are linear actuators.
 10. The structure of claim 9, wherein saidlinear actuators are fluid cylinders with actuating pistons.
 11. Thestructure of claim 10, wherein a fluid circuit is provided for all saidcylinders, said circuit including a source of fluid pressure, a sump andan individual pressure control for each cylinder, and a valve isprovided for each cylinder, all said valves being connected together forsimultaneous operation to (a) admit fluid from said source, (b)discharge fluid to sump, or (c) to close both said connections and opena connection to said individual pressure controls.
 12. The structure ofclaim 1, wherein two pairs of work rolls and three pairs of casters areprovided, the central pairs of casters having no eccentrics, and onlythe two pairs of outer casters are connected to said screwdown controlmeans.
 13. The structure of claim 12, wherein at least one of the pairof central casters carries eccentrics, said eccentrics being connectedto an actuator arranged to shift said casters from one position in whichthe axes of the casters, caster shafts, and eccentrics, and one of thework rolls lie in the same plane, to a symmetrical position with respectto the other work roll, whereby to engage one pair of work rolls whiledisengaging the other.
 14. The structure of claim 1, in combination withmeans to deflect a tenioned exiting strip in a direction normal to itsplane, and proximity measuring gauges disposed opposite each of saideccentrics to measure the deflection of the strip at that point, thesignals from said proximity gauges serving to actuate the individualeccentric control means to produce a strip wherein the tension is evenall the way across.
 15. The structure of claim 14, wherein saiddeflecting means comprise a trough disposed closely adjacent one side ofsaid strip, and means for maintaining a pressure in excess ofatmospheric pressure therein, said proximity gauges being disposed onthe side of said strip opposite said trough.